CAIT-UTC-NC61 Structural Health Monitoring of Representative Cracks in the Manhattan Bridge FINAL REPORT January 2020 Submitted by: Saeed Babanajad1, PhD Franklin Moon1, PhD Postdoctoral Research Associate Professor of Civil Engineering John Braley1, PhD Farhad Ansari2, PhD Postdoctoral Research Associate Professor of Civil Engineering Emad Norouzzadeh2 Todd Taylor2 PhD Candidate & Research Assistant Research Engineer Sougata Roy1, PhD Ali Maher1, PhD Associate Professor of Civil Engineering Professor of Civil Engineering NYCDOT Project Manager Kevin McAnulty In cooperation with Rutgers, The State University of New Jersey And New York City (NYC) Department of Transportation Disclaimer Statement The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. The Center for Advanced Infrastructure and Transportation (CAIT) is a National UTC Consortium led by Rutgers, The State University. Members of the consortium are the University of Delaware, Utah State University, Columbia University, New Jersey Institute of Technology, Princeton University, University of Texas at El Paso, Virginia Polytechnic Institute, and University of South Florida. The Center is funded by the U.S. Department of Transportation. 2 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. CAIT-UTC-NC61 4. Title and Subtitle 5. Report Date Structural Health Monitoring of Representative Cracks in January 2020 the Manhattan Bridge 6. Performing Organization Code CAIT/Rutgers University 7. Author(s) 8. Performing Organization Report No. 1Babanajad, S., 1Moon, F., 1Braley, J., 2Ansari, F., CAIT-UTC-NC61 2Norouzzadeh, E., 2Taylor, T., 1Sougata, R., and 1Maher, A. 9. Performing Organization Name and Address 10. Work Unit No. 1 Center for Advanced Infrastructure and Transportation (CAIT), Rutgers University, 100 Brett Rd., Piscataway, NJ 08854 11. Contract or Grant No. 2 Smart Sensors and NDT Laboratory, University of Illinois at DTRT13-G-UTC28 Chicago (UIC), 2095 ERF, 842 W Taylor St., Chicago, IL 60607 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Center for Advanced Infrastructure and Transportation Final Report Rutgers, The State University of New Jersey 09/01/2018 - 06/30/2019 100 Brett Road 14. Sponsoring Agency Code Piscataway, NJ 08854 15. Supplementary Notes U.S. Department of Transportation/OST-R 1200 New Jersey Avenue, SE Washington, DC 20590-0001 16. Abstract The Manhattan Bridge in NYC is spanning the East River and connecting the island of Manhattan to Brooklyn. It is subjected to repeated dynamic loads, especially by the transit system trains with the average daily traffic of 1,000 trains/85,000 automobiles per day. As a result of repeated loads, multitudes of cracks have been developed in the floor beams, at bottom cords of trusses, and stringers. In addition, it is clear that the discontinuities at the rail splice details cause significant dynamic amplification as the trains pass over them. As a result, a portion of this bridge was selected for monitoring in order to quantify the dynamic amplification associated with the rail joints and to closely monitor the behavior of existing cracks. This was accomplished by implementing a two-phase approach. During the initial phase, an initial vibration survey of the accessible approach spans was conducted to identify locations of high and low dynamic amplification. During the second phase, a long-term fiber optic sensing system was deployed in the regions identified in the first phase to quantify dynamic amplification as well as monitor the behavior of a few representative cracks. This second monitoring phase was carried out over several months and the results were later analyzed and discussed to assess the condition of the bridge. 17. Key Words 18. Distribution Statement Manhattan Bridge, Structural Health Monitoring, Dynamic Amplification, Rail Splice, Structural Crack, Fiber Optic Sensing, Condition Assessment 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 51 Form DOT F 1700.7 (8-69) 3 Acknowledgments The authors would like to express appreciation to New York City Department of Transportation (NYCDOT) officials, particularly Mr. Kevin McAnulty and Mr. Brian Gill, for providing access and general structural information regarding the Manhattan Bridge. 4 Table of Contents Introduction .................................................................................................................................................. 9 Research Objectives and Scope .................................................................................................................... 9 Overview of Test Segment .......................................................................................................................... 10 Phase 1 – Preliminary Assessment and Vibration Survey ........................................................................... 11 Visual Survey of Bridge Components ...................................................................................................... 11 Initial Monitoring Survey ........................................................................................................................ 13 Phase 2 – Long-term Monitoring ................................................................................................................ 16 Overview of Instrumentation Goals ........................................................................................................ 16 Instrumentation Layout .......................................................................................................................... 17 Sensing and Data Acquisition Systems.................................................................................................... 19 Processor Unit ..................................................................................................................................... 20 Remote Monitoring ............................................................................................................................. 20 Installed Monitoring System ............................................................................................................... 20 Monitoring Software ............................................................................................................................... 24 Data Acquisition Protocol ....................................................................................................................... 24 Results and Discussion ................................................................................................................................ 24 Transit Stringer Results ........................................................................................................................... 27 Floor Beam Results ................................................................................................................................. 37 Summary of Results for Transit and Floor Beams ................................................................................... 43 Crack Sensors Results .............................................................................................................................. 44 Analysis of Train Weight ......................................................................................................................... 46 Conclusions ................................................................................................................................................. 48 References .................................................................................................................................................. 50 5 List of Figures Figure 1 Overview of the Manhattan Bridge ................................................................................................ 9 Figure 2 Layout of the Manhattan Bridge ................................................................................................... 10 Figure 3 Plan view of the Manhattan approach (south side) ..................................................................... 10 Figure 4 Cross-section of the Manhattan approach (south side) ............................................................... 11 Figure 5 Layout view of the Manhattan approach ..................................................................................... 11 Figure 6 Layout view of the Manhattan approach (rail splice condition map) .......................................... 12 Figure 7 Problematic rail splicing joints ...................................................................................................... 13 Figure 8 Accelerometer locations (southbound) ........................................................................................ 14 Figure 9 PCB 393A03 accelerometer .......................................................................................................... 14 Figure 10 Sample of acceleration data ....................................................................................................... 15 Figure 11 Frequency content (FFT) of acceleration